John Lane, PE, Electrical Safety Engineer, AVO Training Institute
The objective of OSHA, NFPA, ASTM, IEEE, and others is to protect the worker from electrical hazards. Potential hazards from electricity include shock, arc-flash, and arc blast. This paper will focus on arc-flash and its analysis. When the insulation medium, between phases or phase and ground, whether air, porcelain, polymer, or other medium can no longer support the applied voltage an electrical arc is formed. A short circuit or insulation breakdown is a switching action that creates a bypass around a circuit which involves either phase-to-phase or phase-to-ground or a combination. The heat generated by the high current flow may melt or vaporize the material and create an arc. This arc-flash creates a brilliant flash, intense heat, and a fast moving pressure wave that propels the arcing products.